Spread of the West Nile virus in Europe

Mosquitoes transmit the West Nile virus in Europe

24/08/2011

The mosquito-borne West Nile fever is spreading throughout Europe. More than seventy years after the discovery of the disease in the West Nile district of Uganda (1937), the virus has reached Europe and, as in the past year, has infected several people in Eastern and Southeastern European countries, reports the Center for Travel Medicine (CRM).

According to reports, 50 infections with the West Nile virus were reported from Albania, Greece, Romania and Russia and a total of 56 infections. Since the pathogens are transmitted by mosquitoes, travelers should protect themselves during their stay in Eastern and Southeastern Europe especially from the nocturnal bloodsuckers, warns the Scientific Director of the CRM, Dr. med. med. Tomas Jelinek. According to the expert, due to the growing spread of the West Nile virus, increasing numbers of cases are expected. In 2010 alone in Greece, 257 people contracted West Nile fever and more than five percent of patients died as a result of the infection.

Renewed increase in the infection rate feared
Due to the increased spread of West Nile virus in Eastern and South-Eastern European countries, a renewed increase in infections is to be expected for this year, said the Scientific Director of CRM. According to the information provided by the CRM, the trend continued in 2011 after a significant increase in infections from previous years had already been recorded last year. Experts like Thomas Jelinek „Expect numerous infections this summer and next fall.“ Those planning a trip to Eastern or South-Eastern Europe should therefore consider sufficient mosquito protection to protect themselves against infection with the West Nile virus, warns the CRM. The health risk of West Nile fever is by no means to be underestimated. In addition to the flu-like symptoms such as fever, muscle and headache accompanied by diarrhea, nausea and vomiting can occur in particularly severe disease (about 0.7 percent of infections) also encephalitis (brain inflammation) and meningitis (meningitis). Because the virus is able to cross the blood-brain barrier. Other disease features of West Nile fever include swollen lymph nodes and a rash on the chest, back and arms in about one-third of patients. Especially for older people with pre-existing conditions, whose immune system is already weakened, infection with the West Nile virus is quite life threatening.

According to the CRM, the first symptoms of West Nile fever usually appear three to six days after infection. However, the disease is so severe in only about one percent of the infected that a treatment is necessary, the experts report. Most people suffer hardly any health problems during the infection. However, this also illustrates how massively the West Nile virus has already spread in Eastern and Southern European countries. For 56 previously reported illnesses, the number of people actually infected could already well exceed 5,000 people. Effective treatment of the disease is still unknown, but with many patients being immune to the virus following a West Nile fever infection, experts predict that any outbreak will further reduce the risk of an epidemic.

The West Nile virus has spread in recent decades from Africa to Europe and North America. While only in recent years, the spread of the virus in Europe has increasingly attracted the attention of experts, the pathogen was already identified in 1999 in birds in Central Park in New York in the United States. Between 2002 and 2007, around one hundred people in the United States died each year from West Nile fever disease. Since then, the number of deaths has fallen to about 50 per year. Concerning the distribution of pathogens, the experts reported that migratory birds often serve as a reservoir for the West Nile virus and mosquitoes are the most common vectors. In particular, the mosquitoes of the Culex genus and the Asian tiger mosquito, which sting birds and humans, are considered as bridge vectors, which allow a transfer from the animal to the human. Thus, effective mosquito repellent (insect repellent and body-covering clothing) is the best way to protect against infection with West Nile Fever.

The Scientific Director of CRM recommends travelers, „especially at dusk and at night to protect against mosquitoes.“ The possibility of a vaccination against the West Nile fever does not exist so far, but who secures his windows and beds with mosquito nets, can significantly reduce the risk of disease, explained Thomas Jelinek. According to the experts, the mosquito nets should have a hole size between 1.2 and 1.5 millimeters, in order to ensure effective mosquito repellent and sufficient air circulation at the same time. According to Jelinek, wearing outdoor clothing and applying mosquito repellent to outdoor areas is recommended, especially in regions with many mosquitoes. (Fp)

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Picture: Peashooter